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Litterfall, which is influenced by physical and biological factors, is a major pathway for carbon and nutrient cycling in forest ecosystems. The purpose of this study was to investigate monthly litterfall production in three forests in Jeju Island differentiated by forest composition and precipitation: Cheongsu ( Quercus glauca as the dominant species; low precipitation), Seonheul b ( Q . glauca as the dominant species; high precipitation), and Seonheul m ( Q . glauca and Pinus thunbergii as the dominant species; high precipitation). Litterfall was collected monthly from April to December 2015 and divided into leaf litter, twig, bark, seeds, and unidentified materials. Seasonal patterns of litterfall production varied across stands according to their species composition. However, the amount of leaf litterfall and total litterfall were comparable among stands, ranging from 362 to 375 g m −2 for leaf litter and 524 g m −2 to 580 g m −2 for total litterfall. Oak leaf litter in May was the highest in all stands, while needle litter was the highest in December in Seonheul m . High twig litterfall in July may be attributable to high rainfall with strong winds and storms during the rainy season. Although forest type and climate factor had no influence on litterfall amounts in this study, the pattern of litterfall production was species dependent, suggesting diverse effects on carbon and nutrient cycling in these forests.

BackgroundIn reclaimed land, the growth environment for plants may be unfavorable and the initial establishment and growth of seedlings could be limited because of low nutrient and water availability. Fertilization and control of understory vegetation that competes with seedlings may be of help in ameliorating soil physical and chemical properties, resulting in better seedling growth and reclamation success. However, the amount of nutrients understory vegetation absorbs in this ecological process has been rarely studied. Thus, we aimed to investigate the effect of soil amendment on biomass production and nutrient uptake by weeds in the nutrient-poor reclaimed area. We applied three levels of torrefied wood chip (TWC; 0, 2.5, and 5 Mg ha−1) and two levels of vermicompost (VC; 0 and 2.7 Mg ha−1) as soil physical improvements and organic soil amendments in reclaimed land in the Republic of Korea, with Populus euramericana used as the crop tree.ResultsTWC did not influence weed biomass, but 2.7 Mg ha−1 VC significantly increased weed biomass by 21% compared to 0 Mg ha−1 VC treatments. Nitrogen (N), phosphorus (P), potassium (K), calcium (Ca), magnesium (Mg), and sodium (Na) concentrations in weeds were the highest in control, but there was no statistical difference among treatments. However, VC treatment did marginally increase nutrient uptake in weeds, especially P, K, Ca, and Na. No treatments influenced crop tree height.ConclusionWe conclude that VC can be used as an organic source of nutrients in reclaimed soil and that weed management is necessary to increase treatment effects on crop trees in this salt-affected reclaimed land.

Urban green infrastructure is increasingly recognized as a core component of urban sustainability, providing regulating ecosystem services (ES) that support climate resilience, environmental quality, and long-term urban livability. However, empirical evidence on the long-term stability of ecosystem services (ES) in rapidly urbanizing cities remains limited. Despite widespread assumptions that urbanization inevitably leads to irreversible ecological decline, few studies have quantitatively examined whether ES can persist, or even recover, over multi-decadal time horizons relevant to sustainable urban development. This study investigates the long-term trajectories of eight urban ES in Seoul, South Korea, across nearly five decades (1978–2025) and eight congressional districts, providing one of the longest temporal assessments of urban ES in East Asia. Using i-Tree Canopy and high-resolution aerial imagery across four benchmark years (1978, 1989, 2010, 2025), this study quantified standardized indicators for carbon sequestration (CSeq), avoided runoff (AVRO), and removal of six atmospheric pollutants (O3, NO2, SO2, CO, PM10, PM2.5). Paired-sample t-tests and Cohen’s dz (effect size) were used to assess within-district temporal shifts and the magnitude of ecological change. Results reveal a pronounced period of early ecological stress during rapid industrialization (1978–1989), with negative standardized effect sizes across all services (dz between −0.65 and −0.72). However, these early losses were not sustained. Structural services such as CSeq and AVRO exhibited long-term functional stability, with effect sizes converging toward zero and the 1978–2025 change in CSeq showing no statistical difference (p = 0.784). Pollutant removal services followed an early-decline–followed-by-recovery trajectory, exemplified by CO removal shifting from a large early decline (dz = −0.72) to a modest positive effect in later decades dz = 0.31). These findings indicate that Seoul’s sustained urban greening and environmental policies were effective in preventing further deterioration and maintaining core ecological functions, even if they produced stabilization rather than significant long-term gains in ES delivery.

The forest understory plays an important role in the carbon and nutrient cycling and forest stability, but cost-efficient quantification of its biomass remains challenging. Most of the existing biomass allometric equations have been developed and designed only for mature forest trees (i.e., Diameter at breast height (DBH) ≥ 10 cm), and those for trees with DBH less than 10 cm are not readily available. In this study, we compared the biomass by plant component (i.e., foliage, branch, and stem) measured by a destructive method with those estimated by the existing biomass allometric equations for understory trees with DBH less than 10 cm in a Pinus rigida plantation. We also developed an allometric biomass equation for the identified understory tree species, namely, Quercus variabilis, Quercus acutissima, Quercus mongolica, Quercus serrata, and Carpinus laxiflora. The estimated biomass using allometric equations for foliage, branch, and stem was lower than the values obtained using the destructive method by 64%, 41%, and 18%, respectively. The biomass allometric equations developed in this study showed high coefficients of determination (mean R2 = 0.970) but varied depending on species and tree part (range: 0.824–0.984 for foliage, 0.825–0.952 for branch, and 0.884–0.999 for the stem, respectively). The computed biomass of the understory vegetation was 22.9 Mg ha−1, representing 12.0% of the total biomass of the P. rigida plantation. The present study demonstrates that understory trees with DBH less than 10 cm account for a considerable portion of carbon stock in forest ecosystems, and therefore suggests that more biomass allometric equations should be optimized for small-DBH trees to improve forest carbon stock estimation.

Knowledge about carbon and nutrient fluxes by litterfall is important for understanding nutrient cycling in geologically unique ecosystems. However, the determination of forest litterfall production patterns is difficult due to many biophysical factors influencing the process. In this study, we (1) quantified the litterfall production and carbon and nutrient fluxes in warm-temperate evergreen forest stands in Jeju Gotjawal and (2) compared these values to those of a typical cool-temperate deciduous forest stand by forest types and climate differences. Litterfall from evergreen broadleaved forests at Cheongsu (CS) and Seonheul (SHb), a mixed forest at Seonheul (SHm) in Jeju Gotjawal, and a deciduous broadleaved forest at Chungnam National University Forest (CNU) was collected for a full two years using litter traps. Samples were sorted into leaves, twigs, barks, seeds, and unidentified materials, and then weighed and measured for C, N, P, K, Ca, and Mg fluxes by litterfall. Results showed that the mean annual litterfall (846.3 g m−2, average of CS, SHb, and SHm) at Jeju Gotjawal was similar to that of CNU (885.5 g m−2), but varied by site in Jeju Gotjawal: CS (933.1 g m−2) was significantly higher than the average of SHb and SHm (802.9 g m−2). Seasonal patterns of litterfall production differed by forest types; evergreen broadleaved forests showed a bimodal peak in fall and spring while deciduous broadleaved forests showed a unimodal peak in fall. Jeju Gotjawal had significantly higher total macronutrient concentrations and contents (except for K) than CNU and they also varied by site in Jeju Gotjawal: CS had higher N, P, Ca, and Mg contents than SHb and SHm. We conclude that litterfall production and nutrient fluxes differed by forest stand as influenced by forest types and climate. Further, our findings are important for understanding carbon and nutrient dynamics in the geologically unique ecosystem of Jeju Gotjawal and other areas with similar characteristics.

It is crucial to evaluate the effects of thinning on litterfall production, soil chemical properties, and fine root dynamics when implementing thinning as a silvilcultural technique to enhance tree growth and timber yield in Pinus koraiensis plantations. Thus, we determined the 10-year effects (2007–2017) of different thinning intensities on litterfall production, soil chemical properties, and fine root biomass and necromass within a P. koraiensis plantation in South Korea. The soil chemical parameters and fine root biomass and necromass were also compared across three soil depths (0–10, 10–20, and 20–30 cm). Three thinning treatments were employed: no thinning (CON), light thinning (32% removed, LT), and heavy thinning (64% removed, HT). Results revealed that litterfall was consistent across all thinning treatments, but broadleaf species had considerably higher litterfall production at HT stands than at CON/LT stands. Soil chemical properties, except exchangeable K+, were generally lower at LT stands, particularly at a depth of 20–30 cm soil. After ten years, there was a decrease in fine root biomass and necromass with increasing soil depth. Over 80% of fine roots were found in the upper layer (0–20 cm), while very fine roots (0–1 mm) consisted mainly of 47% pine and 53% other species and were concentrated in the 0–10 cm soil depth in HT. In conclusion, different thinning intensities had diverse effects on the parameters measured within the plantation. Future studies can explore how the effects of thinning intensities on litterfall production, soil chemistry, and fine root dynamics affect species diversity, carbon storage, and understory vegetation in P. koraiensis plantations.

Nursery practices are considered major factors influencing seedling quality, which are likely to be maintained in the early establishment phase in the field. Here, we investigated the effects of container depth and substrate heterogeneity on the growth of Populus sibirica nodal seedlings to suggest an effective nursery practice for producing quality seedlings appropriate for forest establishment in a dry environment. We used two substrate heterogeneities (homogeneous and heterogeneous) and two container depth treatments (30 and 60 cm). Variations in root collar diameter (RCD) growth, height growth, stem and root biomass, root to stem ratio, and root mass in the first 15 cm depth from the soil surface across the treatments were computed. Results revealed that both substrate heterogeneity and container depth had no significant effects on the RCD and height growth of P. sibirica seedlings but significantly improved their root and stem biomass. Seedlings in the 60 cm containers generally accumulated higher root biomass than those in the 30 cm containers. There was an interaction effect of container depth and substrate heterogeneity treatments on root and total dry mass, such that seedlings grown in the 60 cm container using heterogeneous substrate resulted in the highest root and total biomass. Analyses of proportional root growth in the upper 15 cm of the containers compared to the total indicated that both the main effects of deeper containers (60 cm) and heterogeneous substrate have fewer roots at this depth, indicating a greater root density in the bottom of the deeper containers. Therefore, deeper containers and heterogeneous substrate may be used as an effective nursery practice to produce seedlings with root traits potentially suitable for harsh conditions, such as arid and semi-arid environments. However, further studies using other seedling morphological traits in conjunction with field-trial tests are needed for a definitive assessment of the effectiveness of deeper containers and heterogeneous substrate in producing good quality seedlings potentially suitable in a dry environment.

Knowledge on growth and nutrient uptake characteristics of urban trees and effective strategies to grow trees can help accomplish the goal of urban afforestation initiatives in a sustainable way. Thus, the study investigated the effects of different vermicompost (VC) application placements on the growth and nutrient uptake of three contrasting tree species (fast-growing Betula platyphylla and Larix kaempferi and slow-growing Chamaecyparis obtusa) to provide implications for growing tree stocks for sustainable urban afforestation programs. Five placement methods were used in the greenhouse trial: no fertilization (CON), surface placement (VCs), subsurface placement at 6-cm depth (VCc), bottom placement (35-cm depth (VCb)), and mixed with soil (VCm). We measured the growth parameters such as height, root collar diameter (RCD), and biomass and analyzed foliar nutrient concentrations in response to different placement treatments of VC. Relative height growth was the highest at VCc (132% (B. platyphylla), 114% (L. kaempferi)) and VCs ((57%) C. obtusa). Significant improvement in aboveground and belowground biomass growth of all species at VCs and VCc compared to the other treatments was also observed. Generally, VC treatments significantly increased N concentration compared to CON in all species. In conclusion, fertilizing the fast- and slow-growing urban tree species using VCs and/or VCc is relevant to growing high quality planting stocks for sustainable urban afforestation purposes.

A harsh environment, slow tree growth, nutrient deficiencies, and competition between trees and weeds can impede forest establishment on reclaimed lands. We investigated the effects of torrefied wood chips (TWC) and vermicompost (VC) soil amendments on the growth of Populus euramericana Guinier, weed biomass, and soil chemical properties on reclaimed land in Saemangeum. The 2.5 Mg ha−1 and 5.0 Mg ha−1 TWC had a similar effect on tree diameter and height growth (i.e., 2.5 = 5.0 > 0 TWC) and tended to have similar, higher effect on the total biomass of P. euramericana than the 0 Mg ha−1. The 2.5 Mg ha−1 TWC resulted in a significantly larger root biomass than the 5.0 Mg ha−1 TWC. The weed biomass was significantly larger at the 2.7 Mg ha−1 VC (i.e., 730.5–810.5 g m−2) than the control (605.1–610.6 g m−2), but VC alone was not effective for tree growth and soil amelioration. The TWC had no effect on weed biomass. Thus, the TWC and VC had contrasting effects on tree growth and weed biomass when they were used as soil amendments on salt-affected reclaimed land. VC application may promote weed proliferation, whereas TWC application may potentially increase the growth of P. euramericana and control weed growth on reclaimed lands. Our results enhance the existing knowledge on tree and weed responses to torrefied wood chips and vermicompost amendments for the sustainable management of salt-affected reclaimed lands.

Background Understanding the processes underlying carbon storage and balance is critical for equipping the terrestrial biosphere to respond to contemporary climatic challenges. However, ecosystem-level estimates and distribution of net primary productivity (NPP), a metric for evaluating forest carbon cycling patterns and dynamics, remain constrained by uneven empirical observations between above- and belowground fractions. We herein quantified the rate and composition of NPP for four stands characteristic of the cool-temperate deciduous ( Larix kaempferi , LK; Quercus mongolica , QM) and evergreen ( Pinus densiflora , PD; Pinus koraiensis , PK) forests of South Korea over a complete annual cycle (2022–2023). Variations in dynamic NPP compartments, particularly (1) canopy litterfall by stand and season and (2) fine root production by stand, diameter class, and depth interval, were further characterized using litter traps and ingrowth cores, respectively. Results Total NPP varied from 1226 ± 101 to 1796 ± 154 g m −2  yr −1 , with 78–84% allocated aboveground and 16–22% belowground. LK and QM exhibited total NPP up to 46% higher than PD and PK. Both litterfall and fine root production differed considerably across stands, decreasing in the order of QM > PK > PD > LK for litterfall and QM & PD > LK & PK for fine root production. Litterfall peaked in autumn, similar to the leaf phenological rhythm of many temperate deciduous species. In contrast, fine root production showed a negative vertical distribution with depth, which is consistent with decreasing nutrient availability and increasing mechanical impedance along the soil profile. Conclusions By disentangling the contribution levels and dynamic patterns of each NPP compartment, our findings demonstrate a strong inclination toward aboveground NPP investment when belowground resources are not limiting. In other words, an adequate nutrient supply enables plants to modify their priority allocation from fine root maintenance to internal resource transport, leaf production, canopy expansion, reproduction, and other critical aboveground functions. Such information underscores the necessity for forest management strategies that target soil fertility to strengthen not only canopy productivity and CO 2 sequestration but also ecosystem resilience by reinforcing allocation patterns that sustain high NPP and safeguard forests against shifting climate conditions.